This invention relates to a steering module provided at the center of a steering section of an automobile, and more particularly to the structure of a switch module coupled to the steering module.
Recently, an automobile has been improved in the automation of various operations. With this, travel controlling switches, radio operating switches, etc. are collectively provided at the steering section. A variety of steering switch modules of this type are available. Japanese Patent Unexamined Publication No. Hei 2-95949 has disclosed one example of the steering switch module which is designed as follows:
That is, as shown in FIG. 11, a pad 81 is provided at the center of a steering handle 80, and a car radio operating section 82, and a telephone operating section 83 are provided on the pad 87.
The internal structure of the pad 81 is shown in FIG. 12. A membrane switch sheet 85, and the pad 81 are fixedly mounted on a printed circuit board 86, and movable operating keys 82 and 83 are provided on the pad 81. The membrane switch sheet 85 comprises: a spacer; and a thin sheet having electrodes at positions corresponding to those of the operating keys 82 and 83.
The printed circuit board 86 has rectangular openings 87 at the positions corresponding to those of the operating keys 82. Around each of the openings 87, an elliptic contact is formed as a low electrode. Furthermore, the printed circuit board 86 has elliptic contacts at the positions corresponding to those of the telephone operating key 83, and near each of the elliptic contacts a rectangular or square opening 88 is provided so that a light emitting diode is set in it.
In the above-described steering switch module, the membrane switch sheet 85 and the pad 81 are fixedly mounted on the printed circuit board 86 including the contracts and the output circuit. Hence, the resultant switch module is relatively thin, and small in the number of components.
However, the above-described switch module is rather troublesome to install, because it includes no connecting circuit element which is used for the connection of a wire harness laid in the vehicle body. More specifically, in coupling the switch module to the steering section, it is necessary to additionally perform a connector connecting operation.
Furthermore, the switches on the switch module are limited in function, and it is impossible to mount switches on it, which have other functions.
One of the current technical tendencies of automobiles is to improve the safety. As one link in the improvement of safety, air bags are mounted in the vehicle. However, as for the above-described switch module, the provision of air bags are not taken into consideration. Hence, the switch module is not practical in use.